Radiation image conversion panel, scintillator panel, and radiation image sensor

ABSTRACT

The radiation image conversion panel in accordance with the present invention has an aluminum substrate; an alumite layer formed on a surface of the aluminum substrate; a metal film, provided on the alumite layer, having a radiation transparency and a light reflectivity; a protective film covering the metal film and having a radiation transparency and a light transparency; and a converting part provided on the protective film and adapted to convert a radiation image.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiation image conversion panel, ascintillator panel, and a radiation image sensor which are used inmedical and industrial x-ray imaging and the like.

2. Related Background Art

While x-ray sensitive films have conventionally been in use for medicaland industrial x-ray imaging, radiation imaging systems using radiationdetectors have been coming into widespread use from the viewpoint oftheir convenience and storability of imaging results. In such aradiation imaging system, pixel data formed by two-dimensionalradiations are acquired by a radiation detector as an electric signal,which is then processed by a processor, so as to be displayed on amonitor.

Known as a typical radiation detector is one having a structure bondinga radiation image conversion panel (which will be referred to as“scintillator panel” in the following as the case may be), in which ascintillator for converting a radiation into visible light is formed ona substrate such as aluminum, glass, or fused silica, to an image pickupdevice. In this radiation detector, a radiation incident thereon fromthe substrate side is converted into light by the scintillator, and thusobtained light is detected by the image pickup device.

In the radiation image conversion panels disclosed in Japanese PatentApplication Laid-Open Nos. 2006-113007 and HEI 4-118599, a stimulablephosphor is formed on an aluminum substrate having a surface formed withan alumite layer. The radiation image conversion panel having astimulable phosphor formed on a substrate will be referred to as“imaging plate” in the following as the case may be.

SUMMARY OF THE INVENTION

In the above-mentioned radiation image conversion panel, however, thealumite layer has a low reflectance for the light emitted from ascintillator or a phosphor such as stimulable phosphor, whereby theradiation image conversion panel may fail to attain a sufficiently highluminance. Also, cracks, pinholes, and the like may be formed in thealumite layer by the heat generated when vapor-depositing thescintillator or stimulable phosphor onto the aluminum substrate, forexample. As a result, the aluminum substrate and an alkali halidescintillator or stimulable phosphor may react with each other, therebycorroding the aluminum substrate. Though resistant against thecorrosion, the alumite layer may corrode by reacting with thescintillator. The corrosion affects resulting images. Even if only aminute point is corroded, the reliability of a captured image utilizedfor an image analysis will deteriorate. The corrosion may increase astime passes. While the radiation image conversion panel is required tohave uniform luminance and resolution characteristics within thesubstrate surface, the substrate is harder to manufacture as it islarger in size.

In view of the circumstances mentioned above, it is an object of thepresent invention to provide a radiation image conversion panel, ascintillator panel, and a radiation image sensor which can preventaluminum substrates from corroding, while having a high luminance.

For solving the problem mentioned above, the radiation image conversionpanel in accordance with the present invention comprises an aluminumsubstrate; an alumite layer formed on a surface of the aluminumsubstrate; a metal film, provided on the alumite layer, having aradiation transparency and a light reflectivity; a protective filmcovering the metal film and having a radiation transparency and a lighttransparency; and a converting part provided on the protective film andadapted to convert a radiation image.

The scintillator panel in accordance with the present inventioncomprises an aluminum substrate; an alumite layer formed on a surface ofthe aluminum substrate; a metal film, provided on the alumite layer,having a radiation transparency and a light reflectivity; a protectivefilm covering the metal film and having a radiation transparency and alight transparency; and a scintillator provided on the protective film.

The radiation image sensor in accordance with the present inventioncomprises a radiation image conversion panel including an aluminumsubstrate, an alumite layer formed on a surface of the aluminumsubstrate, a metal film which is provided on the alumite layer and has aradiation transparency and a light reflectivity, a protective filmcovering the metal film and having a radiation transparency and a lighttransparency, and a converting part provided on the protective film andadapted to convert a radiation image; and an image pickup device forconverting light emitted from the converting part of the radiation imageconversion panel into an electric signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly broken perspective view schematically showing ascintillator panel in accordance with a first embodiment;

FIG. 2 is a sectional view taken along the line II-II shown in FIG. 1;

FIG. 3 is a graph showing an example of AES spectrum of the alumitelayer in the scintillator panel in accordance with the first embodiment;

FIG. 4 is a graph showing an example of AES spectrum of the metal filmin the scintillator panel in accordance with the first embodiment;

FIGS. 5A to 5C are process sectional views schematically showing anexample of the method of manufacturing a scintillator panel inaccordance with the first embodiment;

FIGS. 6A to 6D are process sectional views schematically showing theexample of the method of manufacturing a scintillator panel inaccordance with the first embodiment;

FIG. 7 is a diagram showing an example of radiation image sensorincluding the scintillator panel in accordance with the firstembodiment;

FIG. 8 is a view showing another example of radiation image sensorincluding the scintillator panel in accordance with the firstembodiment;

FIG. 9 is a sectional view schematically showing the scintillator panelin accordance with a second embodiment;

FIG. 10 is a sectional view schematically showing the scintillator panelin accordance with a third embodiment;

FIG. 11 is a cross-sectional SEM photograph of an example of thescintillator panel in accordance with the third embodiment;

FIG. 12 is a sectional view schematically showing the scintillator panelin accordance with a fourth embodiment;

FIG. 13 is a sectional view schematically showing the scintillator panelin accordance with a fifth embodiment; and

FIG. 14 is a sectional view schematically showing the scintillator panelin accordance with a sixth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, preferred embodiments of the present invention will beexplained in detail with reference to the accompanying drawings. Foreasier understanding of the explanation, the same constituents in thedrawings will be referred to with the same numerals whenever possiblewhile omitting their overlapping descriptions. The dimensions of thedrawings include parts exaggerated for explanations and do not alwaysmatch dimensional ratios in practice.

First Embodiment

FIG. 1 is a partly broken perspective view showing a scintillator panel(an example of radiation image conversion panel) in accordance with afirst embodiment. FIG. 2 is a sectional view taken along the line II-IIshown in FIG. 1. As shown in FIGS. 1 and 2, the scintillator panel 10comprises an aluminum substrate 12, an alumite layer 14 formed on asurface of the aluminum substrate 12, and an intermediate film 16 whichis provided on the alumite layer 14 and has a radiation transparency.The alumite layer 14 and intermediate film 16 are in close contact witheach other. The scintillator panel 10 also includes a metal film 18which is provided on the intermediate film 16 and has a radiationtransparency and a light reflectivity, an oxide layer 20 covering themetal film 18 and having a radiation transparency and a lighttransparency, a protective film 22 covering the oxide layer 20 andhaving a radiation transparency and a light transparency, and ascintillator 24 (an example of a converting part adapted to convert aradiation image) provided on the protective film 22. The intermediatefilm 16, metal film 18, oxide layer 20, protective film 22, andscintillator 24 are in close contact with each other.

In this embodiment, the aluminum substrate 12, alumite layer 14,intermediate film 16, metal film 18, and oxide layer 20 are totallysealed with the protective film 22. The protective film 22 prevents themetal film 18 from corroding because of pinholes and the like formed inthe oxide layer 20. Also, the aluminum substrate 12, alumite layer 14,intermediate film 16, metal film 18, oxide layer 20, protective film 22,and scintillator 24 are totally sealed with a protective film 26.

When a radiation 30 such as x-ray is incident on the scintillator 24from the aluminum substrate 12 side, light 32 such as visible light isemitted from the scintillator 24. Therefore, when a radiation image isincident on the scintillator panel 10, the scintillator 24 converts theradiation image into a light image. The radiation 30 successively passesthrough the protective film 26, protective film 22, aluminum substrate12, alumite layer 14, intermediate film 16, metal film 18, oxide layer20, and protective film 22, thereby reaching the scintillator 24. Thelight 32 emitted from the scintillator 24 is transmitted through theprotective film 26 to the outside, while passing through the protectivefilm 22, so as to be reflected by the metal film 18 and oxide layer 20to the outside. The scintillator panel 10 is used for medical andindustrial x-ray imaging and the like.

The aluminum substrate 12 is a substrate mainly made of aluminum, butmay contain impurities and the like. Preferably, the thickness of thealuminum substrate 12 is 0.3 to 1.0 mm. When the thickness of thealuminum substrate 12 is less than 0.3 mm, the scintillator 24 tends tobe easy to peel off as the aluminum substrate 12 bends. When thethickness of the aluminum substrate 12 exceeds 1.0 mm, the transmittanceof the radiation 30 tends to decrease.

Layer 14 is made of porous aluminum oxide formed by anodic oxidation ofaluminum (i.e. alumite). The alumite layer 14 makes it harder to damagethe aluminum substrate 12. If the aluminum substrate 12 is damaged, thereflectance of the aluminum substrate 12 will be less than a desirablevalue, whereby no uniform reflectance will be obtained within thesurface of the aluminum substrate 12. Whether the aluminum substrate 12is damaged or not can be inspected visually, for example. The alumitelayer 14 may be formed on the aluminum substrate 12 on only one side tobe formed with the scintillator 24, on both sides of the aluminumsubstrate 12, or such as to cover the aluminum substrate 12 as a whole.Forming the alumite layer 14 on both sides of the aluminum substrate 12can reduce the warpage and flexure of the aluminum substrate 12, andthus can prevent the scintillator 24 from being unevenlyvapor-deposited. Forming the alumite layer 14 can also erase streaksoccurring when forming the aluminum substrate 12 by rolling. Therefore,even when a reflecting film (metal film 18 and oxide layer 20) is formedon the aluminum substrate 12, a uniform reflectance can be obtainedwithin the surface of the aluminum substrate 12 in the reflecting film.Preferably, the thickness of the alumite layer 14 is 10 to 5000 nm. Whenthe thickness of the alumite layer 14 is less than 10 nm, the damageprevention effect of the aluminum substrate 12 tends to decrease. Whenthe thickness of the alumite layer 14 exceeds 5000 nm, the alumite layer14 tends to peel off in particular in corner parts of the aluminumsubstrate 12, thereby causing large cracks in the alumite layer 14 anddeteriorating the moisture resistance of the alumite layer 14. In oneexample, the thickness of the alumite layer 14 is 1000 nm. The thicknessof the alumite layer 14 is appropriately determined according to thesize and thickness of the aluminum substrate 12.

FIG. 3 is a graph showing an example of AES spectrum of the alumitelayer in the scintillator panel in accordance with the first embodiment.This example conducts an element analysis in the thickness direction ofthe alumite layer 14 by sputter-etching the alumite layer 14 with argonions for 31 minutes. In this case, aluminum, oxygen, and argon aredetected. Here, argon derives from the argon ions at the time of sputteretching, and thus is not an element contained in the alumite layer 14.Therefore, the alumite layer 14 in this example contains aluminum andoxygen.

Reference will be made to FIGS. 1 and 2 again. The intermediate film 16and protective films 22 and 26 are organic or inorganic films, which maybe made of materials different from each other or the same material. Theintermediate film 16 and protective films 22 and 26 are made ofpolyparaxylylene, for example, but may also be of xylylene-basedmaterials such as polymonochloroparaxylylene, polydichloroparaxylylene,polytetrachloroparaxylylene, polyfluoroparaxylylene,polydimethylparaxylylene, and polydiethylparaxylylene. The intermediatefilm 16 and protective films 22 and 26 may be made of polyurea,polyimide, and the like, for example, or inorganic materials such asLiF, MgF₂, SiO₂, Al₂O₃, TiO₂, MgO, and SiN. The intermediate film 16 andprotective films 22 and 26 may also be formed by combining inorganic andorganic films. In one example, the intermediate film 16 and protectivefilms 22 and 26 have a thickness of 10 μm each. The intermediate film 16reduces minute irregularities of the alumite layer 14, therebyadvantageously acting for forming the metal film 18 having a uniformthickness on the alumite layer 14.

The metal film 18 is constructed by Al, for example, but may also bemade of Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, Au, or the like. Among them, Alor Ag is preferred. The metal film 18 may also contain elements such asoxygen other than metal elements. The metal film 18 may be constitutedby a plurality of metal films, e.g., a Cr film and an Au film providedon the Cr film. Preferably, the thickness of the metal film 18 is 50 to200 nm. In one example, the thickness of the metal film 18 is 70 nm.When an aluminum film is used as the metal film 18, it may be analyzedby AES (Auger Electron Spectroscopy) as an incomplete aluminum oxidedepending on the vapor deposition condition and the processing after thevapor deposition.

FIG. 4 is a graph showing an example of AES spectrum of the metal filmin the scintillator panel in accordance with the first embodiment. Thisexample conducts an element analysis in the thickness direction of themetal layer 18 by sputter-etching the metal film 18 with argon ions for20 minutes. In this case, aluminum, oxygen, and argon are detected.Here, argon derives from the argon ions at the time of sputter etching,and is not an element contained in the metal film 18. Though containingoxygen, the metal film 18 can clearly be distinguished from the alumitelayer 14 in view of their AES spectra forms.

Reference will be made to FIGS. 1 and 2 again. The oxide layer 20 ismade of a metal oxide, SiO₂, TiO₂, or the like, for example. The oxidelayer 20 may be constituted by a plurality of oxide layers made ofmaterials different from each other, e.g., an SiO₂ film and a TiO₂ film.In one example, the thickness of the SiO₂ film is 80 nm while thethickness of the TiO₂ film is 50 nm. The thickness and number oflaminated layers of the SiO₂ and TiO₂ films are determined in view ofthe reflectance for the wavelength of light 32 emitted from thescintillator 24. The oxide layer 20 also functions to prevent the metalfilm 18 from corroding.

The scintillator 24 is smaller than the aluminum film 12 when seen inthe thickness direction of the aluminum substrate 12. For example, thescintillator 24 is constituted by a phosphor which converts theradiation into visible light, and is made of a columnar crystal or thelike of CsI doped with Tl, Na, or the like. The scintillator 24 has astructure provided with a forest of columnar crystals. The scintillator24 may also be made of Tl-doped NaI, Tl-doped KI, or Eu-doped LiI. Astimulable phosphor such as Eu-doped CsBr may be used in place of thescintillator 24. The thickness of the scintillator 24 is preferably 100to 1000 μm, more preferably 450 to 550 μm. Preferably, the averagecolumn diameter of the columnar crystals constituting the scintillator24 is 3 to 10 μm.

As explained in the foregoing, the scintillator panel 10 comprises thealuminum substrate 12; the alumite layer 14 formed on the surface of thealuminum substrate 12; the metal film 18, provided on the alumite layer14, having a radiation transparency and a light reflectivity; theprotective film 22 covering the metal film 18 and having a radiationtransparency and a light transparency; and the scintillator 24 providedon the protective film 22. Therefore, the light 32 emitted from thescintillator 24 is reflected by the metal film 18, whereby thescintillator panel 10 can attain a high luminance. Since the metal film18 and protective film 22 are provided between the alumite layer 14 andscintillator 24, the aluminum substrate 12 and scintillator 24 can bekept from reacting with each other even if the alumite layer 14 isformed with cracks, pinholes, and the like. As a consequence, thealuminum substrate 12 can be prevented from corroding. Forming thealumite layer 14 can further erase damages to the surface of thealuminum substrate 12, whereby uniform luminance and resolutioncharacteristics can be obtained within the surface of the scintillatorpanel 10.

The scintillator panel 10 further comprises the radiation-transparentintermediate film 16 provided between the alumite layer 14 and metalfilm 18. This can flatten the surface of the alumite layer 14, therebyimproving the flatness of the metal film 18. Therefore, the in-surfaceuniformity in reflectance of the metal film 18 improves. It can alsoenhance the adhesion between the alumite layer 14 and metal film 18. Itcan further prevent moisture, scintillator constituent materials, andthe like from passing through cracks, pinholes, and the like formed inthe alumite layer 14. Therefore, the aluminum substrate 12 is furtherprevented from corroding.

The scintillator panel 10 further comprises the oxide layer 20 coveringthe metal film 18 and having a radiation transparency and a lighttransparency. This can improve the moisture resistance of the metal film18 and prevent the metal film 18 from being damaged. It can also enhancethe reflectance of the metal film 18.

FIGS. 5A to 5C and 6A to 6D are process sectional views schematicallyshowing an example of the method of manufacturing a scintillator panelin accordance with the first embodiment. The method of manufacturing thescintillator panel 10 will now be explained with reference to FIGS. 5Ato 5C and 6A to 6D.

First, as shown in FIG. 5A, the aluminum substrate 12 is prepared.Subsequently, as shown in FIG. 5B, the alumite layer 14 is formed byanodic oxidation on a surface of the aluminum substrate 12. For example,the aluminum substrate 12 is electrolyzed by an anode in an electrolytesuch as dilute sulfuric acid, so as to be oxidized. This forms thealumite layer 14 constituted by an assembly of hexagonal columnar cellseach having a fine hole at the center. The alumite layer 14 may bedipped in a dye, so as to be colored. This can improve the resolution orenhance the luminance. After being formed, the alumite layer 14 issubjected to a sealing process for filling the fine holes.

Next, as shown in FIG. 5C, the intermediate film 16 is formed on thealumite layer 14 by using CVD. Further, as shown in FIG. 6A, the metalfilm 18 is formed on the intermediate film 16 by using vacuum vapordeposition. The metal film 18 is made of aluminum having a purity of99.9%, for example. Thereafter, as shown in FIG. 6B, the oxide layer 20is formed on the metal film 18. Next, as shown in FIG. 6C, theprotective film 22 is formed by using CVD so as to seal the aluminumsubstrate 12, alumite layer 14, intermediate film 16, metal film 18, andoxide layer 20 as a whole. Further, as shown in FIG. 6D, thescintillator 24 is formed on the protective film 22 on the oxide layer20 by using vapor deposition. Subsequently, as shown in FIGS. 1 and 2,the protective film 26 is formed by using CVD so as to seal the aluminumsubstrate 12, alumite layer 14, intermediate film 16, metal film 18,oxide layer 20, protective film 22, and scintillator 24 as a whole.Thus, the scintillator panel 10 is manufactured. The sealing with theprotective films 22 and 26 can be realized by lifting the side of thealuminum substrate 12 opposite from the scintillator forming surfacefrom a substrate holder at the time of CVD. An example of such method isone disclosed in U.S. Pat. No. 6,777,690. This method lifts the aluminumsubstrate 12 by using pins. In this case, no protective film is formedon minute contact surfaces between the aluminum substrate 12 and thepins.

FIG. 7 is a diagram showing an example of radiation image sensorincluding the scintillator panel in accordance with the firstembodiment. The radiation image sensor 100 shown in FIG. 7 comprises thescintillator panel 10 and an image pickup device 70 which converts thelight 32 emitted from the scintillator 24 of the scintillator panel 10into an electric signal. The light 32 emitted from the scintillator 24is reflected by a mirror 50, so as to be made incident on a lens 60. Thelight 32 is converged by the lens 60, so as to be made incident on theimage pickup device 70. One or a plurality of lenses 60 may be provided.

The radiation 30 emitted from a radiation source 40 such as x-ray sourceis transmitted through an object to be inspected which is not depicted.The transmitted radiation image is made incident on the scintillator 24of the scintillator panel 10. As a consequence, the scintillator 24emits a visible light image (the light 32 having a wavelength to whichthe image pickup device 70 is sensitive) corresponding to the radiationimage. The light 32 emitted from the scintillator 24 is made incident onthe image pickup device 70 by way of the mirror 50 and lens 60. Forexample, CCDs, flat panel image sensors, and the like can be used as theimage pickup device 70. Thereafter, an electronic device 80 receives theelectric signal from the image pickup device 70, whereby the electricsignal is transmitted to a workstation 90 through a lead 36. Theworkstation 90 analyzes the electric signal, and outputs an image onto adisplay.

The radiation image sensor 100 comprises the scintillator panel 10 andthe image pickup device 70 adapted to convert the light 32 emitted fromthe scintillator 24 of the scintillator panel 10 into the electricsignal. Therefore, the radiation image sensor 100 can prevent thealuminum substrate 12 from corroding, while having a high luminance.

FIG. 8 is a view showing another example of radiation image sensorincluding the scintillator panel in accordance with the firstembodiment. The radiation image sensor 100 a shown in FIG. 8 comprisesthe scintillator panel 10, and an image pickup device 70 which isarranged so as to oppose the scintillator panel 10 and adapted toconvert light emitted from the scintillator 24 into an electric signal.The scintillator 24 is arranged between the aluminum substrate 12 andimage pickup device 70. The light-receiving surface of the image pickupdevice 70 is arranged on the scintillator 24 side. The scintillatorpanel 10 and image pickup device 70 may be joined together or separatedfrom each other. When joining them, an adhesive may be used, or anoptical coupling material (refractive index matching material) may beutilized so as to reduce the loss of the emitted light 32 in view of therefractive indexes of the scintillator 24 and protective film 26.

The radiation image sensor 100 a comprises the scintillator panel 10 andthe image pickup device 70 adapted to convert the light 32 emitted fromthe scintillator 24 of the scintillator panel 10 into the electricsignal. Therefore, the radiation image sensor 100 a can prevent thealuminum substrate 12 from corroding, while having a high luminance.

Second Embodiment

FIG. 9 is a sectional view schematically showing the scintillator panelin accordance with a second embodiment. The scintillator panel 10 ashown in FIG. 9 has the same structure as that of the scintillator panel10 except that the intermediate film 16 totally seals the aluminumsubstrate 12 and alumite layer 14. Therefore, the scintillator panel 10a not only exhibits the same operations and effects as those of thescintillator 10, but further improves the moisture resistance of thealuminum substrate 12, and thus can more reliably prevent the aluminumsubstrate 12 from corroding.

Third Embodiment

FIG. 10 is a sectional view schematically showing the scintillator panelin accordance with a third embodiment. The scintillator panel 10 b shownin FIG. 10 has the same structure as that of the scintillator panel 10except that it lacks the intermediate film 16. Therefore, thescintillator panel 10 b not only exhibits the same operations andeffects as those of the scintillator 10, but can also simplify thestructure. FIG. 11 is a cross-sectional SEM photograph of an example ofthe scintillator panel in accordance with the third embodiment.

When forming the metal film 18 on the alumite layer 14, the thickness ofthe metal film 18 is preferably 50 to 200 nm in view of a uniformreflection characteristic, adhesion strength, and the like of the metalfilm 18. Preferably, for keeping the surface state of the aluminumsubstrate 12 from affecting the metal film 18, the thickness of thealumite layer 14 is greater than that of the metal film 18. In oneexample, the thickness of the alumite layer 14 is 1000 nm.

Fourth Embodiment

FIG. 12 is a sectional view schematically showing the scintillator panelin accordance with a fourth embodiment. The scintillator panel 10 cshown in FIG. 12 has the same structure as that of the scintillatorpanel 10 except that it lacks the oxide layer 20. Therefore, thescintillator panel 10 c not only exhibits the same operations andeffects as those of the scintillator 10, but can also simplify thestructure.

Fifth Embodiment

FIG. 13 is a sectional view schematically showing the scintillator panelin accordance with a fifth embodiment. The scintillator panel 10 d shownin FIG. 13 has the same structure as that of the scintillator panel 10 cexcept that the intermediate film 16 totally seals the aluminumsubstrate 12 and alumite layer 14. Therefore, the scintillator panel 10d not only exhibits the same operations and effects as those of thescintillator 10 c, but further improves the moisture resistance of thealuminum substrate 12, and thus can more reliably prevent the aluminumsubstrate 12 from corroding.

Sixth Embodiment

FIG. 14 is a sectional view schematically showing the scintillator panelin accordance with a sixth embodiment. The scintillator panel 10 e shownin FIG. 14 further comprises a radiation-transparent reinforcement plate28 bonded to the aluminum substrate 12 in addition to the structure ofthe scintillator panel 10. The aluminum substrate 12 is arranged betweenthe reinforcement plate 28 and scintillator 24.

The reinforcement plate 28 is bonded to the aluminum substrate 12 by adouble-sided adhesive tape, an adhesive, or the like, for example.Employable as the reinforcement plate 28 are (1) carbon fiber reinforcedplastics (CFRP), (2) carbon boards (made by carbonizing and solidifyingcharcoal and paper), (3) carbon substrates (graphite substrates), (4)plastic substrates, (5) sandwiches of thinly formed substrates (1) to(4) mentioned above with resin foam, and the like. Preferably, thethickness of the reinforcement plate 28 is greater than the totalthickness of the aluminum substrate 12 and alumite layer 14. Thisimproves the strength of the scintillator panel 10 e as a whole.Preferably, the reinforcement plate 28 is larger than the scintillator24 when seen in the thickness direction of the aluminum substrate 12.Namely, it will be preferred if the reinforcement plate 28 hides thescintillator 24 when seen in the thickness direction of the aluminumsubstrate 12 from the reinforcement plate 28 side. This can prevent ashadow of the reinforcement plate 28 from being projected. Inparticular, this can prevent an image from becoming uneven because ofthe shadow of the reinforcement plate 28 when the radiation image 30having a low energy is used.

The scintillator panel 10 e not only exhibits the same operations andeffects as those of the scintillator panel 10, but can further improvethe flatness and rigidity of the scintillator panel 10 e. Therefore, thescintillator panel 10 e can prevent the scintillator 24 from peeling offas the aluminum substrate 12 bends. Since the radiation image sensor 100shown in FIG. 7 uses the scintillator panel as a single unit, it iseffective to employ the scintillator panel 10 e having a high rigidity.

The reinforcement plate 28 may be bonded to one of the scintillatorpanels 10 a, 10 b, 10 c, 10 d instead of the scintillator panel 10.

Though preferred embodiments of the present invention are explained indetail in the foregoing, the present invention is not limited to theabove-mentioned embodiments and the structures exhibiting variousoperations and effects mentioned above.

For example, the radiation image sensors 100, 100 a may employ one ofthe scintillator panels 10 a, 10 b, 10 c, 10 d, 10 e in place of thescintillator panel 10.

The scintillator panel 10 is not required to have both of theintermediate film 16 and oxide layer 20. The scintillator panels 10, 10a, 10 b, 10 c, 10 d, 10 e may be free of the protective film 26.

Though the above-mentioned embodiments exemplify the radiation imageconversion panel by the scintillator panel, a stimulable phosphor (anexample of a converting part adapted to convert a radiation image) maybe used in place of the scintillator 24, whereby an imaging plate as theradiation image conversion panel can be made. The stimulable phosphorconverts the radiation image into a latent image. This latent image isscanned with laser light, so as to read a visible light image. Thevisible light image is detected by a detector (photosensor such as linesensor, image sensor, and photomultiplier).

1. A radiation image conversion panel comprising: an aluminum substrate;an aluminum oxide layer formed on a surface of the aluminum substrate; ametal film, provided on the aluminum oxide layer, having a lightreflectivity, at least a portion of the aluminum oxide layer beingpositioned between the aluminum substrate and the metal film; aprotective film covering the metal film and having a light transparency,at least a portion of the metal film being positioned between thealuminum oxide layer and the protective film; and a converting partprovided on the protective film and adapted to convert a radiationimage, the converting part comprising a light emitting surface of theradiation image conversion panel, and at least a portion of theprotective film being positioned between the metal film and theconverting part.
 2. A scintillator panel comprising: an aluminumsubstrate comprising a radiation receiving surface of the scintillatorpanel; an aluminum oxide layer formed on a surface of the aluminumsubstrate other than the radiation receiving surface; a metal film,provided on the aluminum oxide layer, having a radiation transparencyand a light reflectivity, at least a portion of the aluminum oxide layerbeing positioned between the aluminum substrate and the metal film; aprotective film covering the metal film and having a radiationtransparency and a light transparency, at least a portion of the metalfilm being positioned between the aluminum oxide layer and theprotective film; and a scintillator provided on the protective film, thescintillator comprising a light emitting surface of the scintillatorpanel, and at least a portion of the protective film being positionedbetween the metal film and the scintillator.
 3. A scintillator panelaccording to claim 2, further comprising a radiation-transparentintermediate film provided between the aluminum oxide layer and themetal film.
 4. A scintillator panel according to claim 3, furthercomprising an oxide layer covering the metal film and having a radiationtransparency and a light transparency.
 5. A scintillator panel accordingto claim 2, further comprising an oxide layer covering the metal filmand having a radiation transparency and a light transparency.
 6. Ascintillator panel according to claim 2, further comprising aradiation-transparent reinforcement plate bonded to the aluminumsubstrate, the aluminum substrate being arranged between thereinforcement plate and the scintillator.
 7. A radiation image sensorcomprising: a radiation image conversion panel including an aluminumsubstrate; an aluminum oxide layer formed on a surface of the aluminumsubstrate; a metal film, provided on the aluminum oxide layer, having alight reflectivity, at least a portion of the aluminum oxide layer beingpositioned between the aluminum substrate and the metal film; aprotective film covering the metal film and having a light transparency,at least a portion of the metal film being positioned between thealuminum oxide layer and the protective film; and a converting partprovided on the protective film and adapted to convert a radiationimage, the converting part comprising a light emitting surface of theradiation image conversion panel, and at least a portion of theprotective film being positioned between the metal film and theconverting part; and an image pickup device for converting light emittedfrom the light emitting surface of the converting part of the radiationimage conversion panel into an electric signal.